Have the resolver emit unique parameter names
Aslo: Update the parser tests to include ':' between parameter name and type.
This functionality landed a few changes up, but I missed this test from the change.
Bug: tint:832
Change-Id: If0d6d3a33bbcd8be4d70ee7182754158ed0da819
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/52641
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>